using photos

you must not upload photos of pupils in school - there are obvious safeguarding issues here.

you must make every effort to use copyright permitted images. Use the advanced search button in Google and select the appropriate image rights as below:
image_rights.jpg
searching in wikimedia commons is a good place to start
make your own images
use the printscreen button on your keyboard to grab pictures of what's going on in a publicly uploaded video or simply to drop in a slice from Windows Journal
use Paint and other simple image editors to crop and resize.